Absolute addresses are processor addresses after any required dynamic address translation and prefixing is performed. The assignment of absolute addresses to the physical main storage hardware was initially done by fixed wiring of the storage array hardware in the storage system. Later processors had several storage array hardware modules, sometimes called basic storage modules (BSMs). Plural BSMs are essential for some types of interleaved storage operations. It was recognized that flexibility was desirable in assigning processor absolute addresses to the BSMs, and this was done by providing manually changeable wiring, via a plugboard.